It is well known in the art to provide a derail for the purpose of derailing a car or locomotive to prevent accidental entry thereof into an area to be protected. Derails arc commonly of a type which are permanently installed on a rail by anchoring a component of the derail to one or more crossties by a plurality of spikes or the like. Such derails may weigh from 150 to 300 pounds, so it is not feasible for a workman to carry them about, and it is not intended that they be removed with any frequency for transfer from one location to another. Such permanently installed derails normally include a derail block or the like which may be moved between an operative derailing position on the rail and an inoperative position alongside the rail.
In addition to permanent type derails as described above, it is also known to provide a lightweight portable derail, and such derails are especially useful to guard areas requiring temporary protection due to men working, the presence of work equipment, occupied bunk cars and other such temporary conditions. It is desirable that such a portable derail weigh less than 50 pounds so that a workman can carry it from place to place, and yet it must be sufficiently sturdy as to effectively derail a heavy car moving at a significant speed.
It is particularly difficult to secure a lightweight portable derail in operative position on a rail so it will not slide along the rail under impact and yet can be readily removed when desired. A common type of portable derail heretofore known includes a large generally C-shaped clamp which extends underneath the rail from the gage side and hooks around an outside flange of the rail base thereby anchoring the derail to the rail member. However, in certain situations, as when the ground is frozen, it is difficult to dig beneath the rail in order to install such a clamp member. Moreover, such a clamp includes a tightening screw and manually operable handle, and due to the location of the clamp it is necessary that the handle be located in the ballast and tie area where it may be difficult to operate.
Another feature common to prior art derails, both of the permanent and portable type, is that they generally must be provided in various sizes to fit different sizes of rail. In particular, a conventional derail is normally made in different sizes depending upon the height of the rail on which it is to be mounted.
The current state of the art in portable derails can be seen in U.S. Pat. No. 4,165,060. Portable derails of this type are commercially available from Western-Cullen-Hayes, Inc. However, these portable derails weigh at least 44 lbs. and are thus still somewhat heavy. Accordingly, it is an object of the present invention to provide a portable derail with a reduced weight in order to further increase and maximize derail portability.